Is there an LPV which ceased to vary?

I seem to remember reading many years ago - probably in 'Burnham's Celestial Handbook' - about a long period variable star which had behaved normally for many decades but had then stopped pulsating altogether. Am I remembering this correctly, and if so, which star was it, and what has it done since Burnham's was published (back in the mid- or late-1970s)? Thanks!

I seem to remember something similar, but I can't remember the exact star. There's a short list of stars in Mattei, Mayall, & Waagen's Maxima and Minima of LPVs, 1949-1975 (published 1990) whose behavior had changed enough to make predictions difficult: W Tau, RT Hya, Y Sco, and SZ And. It is possible that these are simply semiregulars whose (possible?) multiperiodic behavior was simply at a phase where the different periods were interfering destructively, leading to a drop in amplitude. I checked all of these stars, and they're still pulsating with detectable amplitude now. T UMi is a similar star, but its notable that it was a Mira and became a semiregular within the past four decades.

Polaris isn't an LPV (it's a delta Cephei star) but its amplitude dropped away to almost nothing for several years and subsequently started to increase again.

I don't know of any LPV that has ceased. What you might be thinking of is RU Cam, a 22-day irregular variable commonly classified as a CWA type. This star ceased variation for a number of years in that 1970 timeframe, and might have been reported in Burnham's. As Matt mentioned, Polaris nearly ceased pulsation, but was not reported as changing its amplitude until a paper by Ferro Arellano in 1983.

That was RU Cam in Burnham Vol I. -a Cepheid. which apparently ceased to pulsate around 1971.A quick check of the LCG shows the apparent cessation but at the scale I looked it wasn't that clearcut.

Some LPVs have certainly changed their periods and I read an article few years back that suggested Mira underwent a Helium shell flash near the time of its discovery. R Hya was another but there were some challenges to the Shell Flash model v Envelope relaxation.

Z UMa Ceased variability for arounf 1684 days. Ive attached a graph of the light curve and weighted wavelet transforms in 1634 day windows. I've just finished a project on this so if you'd like more information please get in touch.